Rumble strips 'not very effective' for traffic calming, City of Windsor finds

How useful are rumble strips as a traffic calming measure?

Not very, according to a report on a pilot project that installed them in a Windsor residential neighbourhood.

"The conclusion is going to be that rumble strips, on their own... They're not very effective," said Ian Day, City of Windsor manager of traffic operations.

Transverse rumble strips are designed to raise the attention of drivers by generating noise when vehicles go over them.

Since July 2023, there's been a short series of such strips on Grand Marais Road East approaching the stop sign at Pillette Road.

The city installed the strips as a pilot project — launched in response to two incidents in May 2023 when speeding vehicles on Grand Marais Road East went through the intersection and collided with a house.

But both those incidents involved impaired drivers. According to the report, radar data shows the strips haven't made a huge difference on everyday traffic.

Prior to the installation of the strips, the average vehicle speed on Grand Marais Road East at Pillette Road was 38.7 km/h, with 4.7 per cent of vehicles exceeding the street's posted speed limit of 40 km/h.

After installation of the strips, the average vehicle speed on Grand Marais Road East was 36.1 km/h, with 1.9 per cent of vehicles speeding.

Ian Day acknowledged that a 2.6 km/h reduction in average speed and improvement of speeders by less than three percentage points aren't particularly impressive results.

"(Rumble strips) are used on high-speed roadways," Day told CBC Windsor. "Really, they're not as effective under 70 km/h.... because the car speed is already slow enough that it doesn't produce the desire effect."

"On their own, we found that (rumble strips) weren't very successful because of the low speeds on the roadway."

Even before installation, administration knew that rumble strips aren't used in neighbourhood situations like the one at Grand Marais Road East and Pillette Road.

Day said most provinces and jurisdictions don't recommend installing strips in urban environments. British Columbia doesn't allow them within 200 metres of any residence, and Alberta doesn't allow them on roadways with speed limits below 70 km/h.

The Ontario Traffic Manual discourages putting rumble strips in residential areas.

Carl Berkowitz, a U.S.-based traffic engineering expert, reacted with puzzlement when told of the City of Windsor's project.

"Rumble strips are primarily used to keep people in lanes," Berkowitz said. "I've never seen it work very successfully in terms of controlling speed."

"I don't see them changing people. Like, when I go into a village where there are rumble strips, nobody slows down. Nobody changes... Whatever they do before (the strips), they're continuing."

All that said, the City of Windsor's experiment was not an expensive one: Day said the total cost of the project was only around $3,300.

"It's good bang for your buck," Day said. "That's why we felt it's good to have it in our toolbox."

The rumble strips on Grand Marais Road East will be removed at the start of November in preparation for the winter: They're an impediment to snow plows, as are traffic bollards.

The report on the project went before the city's standing committee on the environment, transportation and public safety on Wednesday. It will go before city council at a future date.

But Day pointed out that his department is working on a larger, more comprehensive report, detailing updates to the entire city's traffic calming policy and procedures.